'This Is Spinal Tap' Turns 40: Cast Breaks Down Fan-Favorite Scenes and Origin Story (Flashback)

The cast of 'This Is Spinal Tap' chatted with ET about the 1984 mockumentary's fan-favorite scenes, from airport security discovering Derek Smalls' cucumber to Nigel Tufnel's 'Mach' opera. Christopher Guest, Michael McKean, Harry Shearer and director Rob Reiner recalled the parody movie's origin story.